Roll type drier



NOV. 8, 1938. Q HURXTHAL 2,135,516

ROLL TYPE DRIER Filed March 22, 1937 Patented Nov. 8, 1938 UNITED STATESPATENT OFFICE aom. TYPE mum Application March 22, 1937, Serial No.132,425

5 Claims.

This invention relates to mechanisms for handling continuous webmaterials, wherein the material is threaded back and forth, verticallyor horizontally, between and around two relatively spaced sets or seriesof rolls and advanced there: by in one general direction, as in cloth orpaper driers or other conditioning or treating chambers, etc.

Normally the trunnions of the rolls are rotatably mounted in fixedbearings which maintain the two series of rolls in definite spacedrelation to each other. Under these circumstances, shrinkage of the weblongitudinally, beginning simultaneously with the starting of the dryingof the material and increasing as the drying progresses, places the webunder a constantly increasing tension. Such tension, in many instances,re-

sults in damage to either the web or the mechanism or both.

The above noted condition is further aggravated by the rolls of one orboth series being positively driven constantly from a common source ofmechanical power, all at the same constant uniform speed, which causesthe shrinkage and its resultant tension, occurring between successiverolls, to accumulate or build up progressively, and to reach a maximumbetween the rolls around which the web in its more thoroughly driedstate passes.

Efforts have been made to overcome the above noted difficulty, bydividing the rolls into groups; and by placing a floating free runningroll between successive groups, to rise and fall as the tension of theweb varies; and by using the rise and fall of the floating roll tocontrol a speedchanging mechanism for driving the next sucoeeding groupof rolls at a different speed from that of the preceding group of rolls.

The above noted practice, while it relieves the undesirable condition tosome extent it does not completely overcome the trouble, as the sameundesirable condition obtains, although to a somewhat lesser degree, ineach group of rolls.

The object of the present invention is to eliminate the above notedundesirable condition, by providing a separate individual driving motorfor each roll, or for each alternate roll, or for each roll of anypredetermined number thereof, as will be fully disclosed hereinafter,reference being had to the accompanying drawing, of which:

Fig. 1 diagrammatically illustrates a drier or other treating device forweb materials, including a plurality of independently driven rolls inaccordance with the principles of the present invention;

Fig. 2 is a transverse section taken on the line 2-2; Fig. 1, showingthe individual driving motor of one of the rolls; and

Fig. 3 is a section taken on the line 3-3, Fig. 2.

As shown in Fig. 1, a continuous web a passes alternately around andbetween successive rolls I, i of two separate relatively spaced series Aand B thereof.

I Each roll I is provided with a shaft or trunnions 2 which extendaxially beyond the opposite ends respectively of the roll. Each of theaxial projections I is rotatably mounted in a bearing 3 secured to arigid support 4.

Each of any predetermined number of therolls I, of each or either of theseries A and B, is provided with a separate individual and independentdrive of its own, in the form of an'electric motor l.

The rotor shaft 5a of each motor 5 may be connected to the shaft 2 ofthe particular roll I which is driven by the motor 5 in any suitablemanner, preferably through speed reduction gearin: i.

The rolls i, I may be encased in any suitable enclosure I in which anysuitable web-treating medium may be circulated in any well known manner.

The web a: may be fed into the enclosure 1, to the rolls I therein, at apredetermined definite speed by any suitable means such for example as apair of grip rolls 8, 8. The feed rolls 8, 8 may be driven at anysuitable predetermined speed, variable at the will of the operator, byany suitable means, not shown.

The motors 5 preferably are of a commercially available type known assingle phase shadedpole motors". These motors are particularly adaptedfor use in the present instance because of. certain characteristics ofthis type of motor which permits the motor to be stopped, as byoverloading, for indefinite periods of time, with current flowingthrough the motor windings, without the motor becoming overheated ordamaged. These same characteristics permit the motor to be restricted toany speed within its full range, from its maximum number of revolutionsper minute, when under minimum load, to zero or full stop, underoverload, without harm, by variations occurring in the torque loadapplied to the motor. The characteristics of this type of motor alsoallow the motor to start under full load from a dead stop. 1

In the present instance each motor 5, when supplied with a definiteamount of electric energy, develops a definite amount of power which issuillcient to drive the roll i connected thereto Lil at a normaldefinite speed, under a normal dennite torque load applied, through theweb a: and roll I, to the rotor of the motor 5.

The grip rolls 8, 8 feed the web a: at a definite predetermined rate ofspeed which is less than the maximum peripheral speeds of the advancingrolls I, I. Thus the feed rolls 8, 8 apply a definite resistance to theadvance of the web a: by the rolls I, I and primarily determines thenormal torque load on the motor 5. Any additional amount of resistanceto the rotation of any of the rolls I, applied by the web a, will resultin proportionate reductions in the speeds of the motors whichrespectively drive such rolls.

The intensity of the pull on the web by the rolls I, I, and theconsequential tension of the web remain substantially constant at allspeeds of the motors. In other words, the web-advancing effort exertedon the web by each roll remains substantially constant even though theresistance to the rotation of the roll and the peripheral speed of theroll may vary in accordance with variations occurring in the torque loadof the roll as applied thereto by the web.

Under the above noted conditions, assuming that a moistened web isthreaded around the rolls of the series A and B alternately and fed tothe initial roll I in the casing I at a predetermined speed by the feedrolls 8, 8, and all the motors are supplied with equal energy, all therolls I, I would rotate at the same peripheral speed and the web a:would be advanced at a constant uniform rate of speed, under a constantuniform tension, throughout its passage around and between the rolls I,I. The web would be delivered from the last roll at said same rate atwhich it was fed to the first roll.

If heated air or other drying medium be applied to the web during itspassage from the first to the last of the rolls, the web will begin todry immediatelyupon, or in a short time after, its entrance into thechamber I, and the drying will progress as the web continues to beadvanced by the rolls I, I successivelyl As the drying progressivelyincreases, the web will shrink and the shrinkage will progress andincrease with the drying. As the shrinkage increases, the length of theweb between the terminal rolls, i. e. first and last roll, willdecrease. Thus the web will be delivered from the last roll at a lowerrate than it is being fed to the first roll. This has the effect ofprogressively increasing the resistance to the rotation of thesuccessive rolls I and under the conditions of operation of the motors5, as noted above, the relative speeds of the successive rolls I, I willautomatically decrease and maintain a substantially uniform tension onthe web constantly, thereby eliminating the undesirable conditions anddamages attending the drying of webs under current practices.

The speeds at which the motors'would operate under the circumstancesjust described are not the maximum speeds of the motors, as above noted.Therefore, if for any reason the web would stretch, intentionally orotherwise, the drag or resistance presented to the rotation of the rollsby the web would decrease and permit the motors to increase theirspeeds. Thus, in cases where a web would stretch progressively, i. e.where the web would be moistened after entering the chamber I instead ofbeing dried therein, the rate of discharge of the web from the last rollwould be greater than the rate of feed to the first roll, and theintermediate rolls would increase their speeds accordingly to compensatefor the variations in the length of the web and thereby maintain the webunder substantially uniform tension in its passage through the rolls.

From the above, it will be clear that in using an independent drivingmotor for each of any desired number of the web-advancing rolls of anapparatus for treating webs, wherein each of the roll-driving motors hasthe characteristics above noted, it is only necessary to feed the webinto the treating chamber at any predetermined speed and the rolls willdrive the web through regardless of shrinkage and stretch, so long asthe web is not fed in faster than the predetermined maximum speed of therolls which are driven by the motors respectively.

I claim:

1. In a web-treating apparatus, the combination of a plurality ofweb-advancing rolls around which the web passes successively, means forfeeding the web to said rolls at a predetermined rate of speed, and anindependently operable driving motor for each one of a predeterminednumber of said rolls, the speeds of said motors being controlledcollectively by the web and the rate of feeding thereof to said rolls bysaid feeding means and independently by variations occurring in theamount of resistance presented to the rotations of the respective rollsas applied thereto by the web intermediate the terminal rolls of saidplurality.

2. In a web-treating apparatus, the combination of a plurality ofweb-advancing rolls around which the web passes successively, means forfeeding the web to said rolls at a predetermined rate of speed, and anindependently operable electric driving motor for each one of apredetermined number of said rolls, the speeds of said electric motorsbeing controlled collectively by the web and the rate of feeding thereofto said rolls by said feeding means and independently by variationsoccurring in the amount of resistance presented to the rotations of therespective rolls as applied thereto by the web intermediate the terminalrolls of said plurality.

3. In a web-treating apparatus, the combination of a plurality ofweb-advancing rolls around which the web passes successively, means forfeeding the web to said rolls at a predetermined rate of speed, and anindependently operable electric driving motor of the single phaseshadedpole type for each one of a predetermined number of said rolls,the speeds of said electric motors being controlled collectively by theweb and the rate of feeding thereof to said rolls by said feeding meansand independently by variations occurring in the amount of resistancepresented to the rotations of the respective rolls as applied thereto bythe web intermediate the terminal rolls 01' said plurality.

4. In a. web-treating apparatus, the combination of a plurality ofweb-advancing rolls around which the web passes successively, means forfeeding the web to said rolls at a predetermined rate of speed, and anindependently operable electric driving motor of the single phaseshadedpole type for each one of a predetermined number of said rolls,the speeds of said electric motors being controlled collectively by theweb and the rate of feeding thereof to said rolls by said feeding meansand independently by variations occurring in the amount of resistancepresented to the rotations of the respective rolls as applied thereto bythe web intermediate the terminal rolls of said plurality, said feedingmeans and driving motors cooperating to maintain the web undersubstantially constant tension between said terminal rolls.

5. In a web-treating apparatus, the combination of a plurality ofweb-advancing rolls, means for feeding a web to said rolls at apredetermined rate of speed, an independently operable driving motor foreach one of a predetermined number of said rolls, means operablycoupling each driving motor to its associated roll, the speeds of theindependently driven rolls being directly governed by the rate orfeeding of the web to said rolls and varying proportionately withvariations occurring in the amount of resistance presented to therespective rolls by variations occurring in the length of the webintermediate the terminal rolls of said plurality, said motors throughsaid couplings independently maintaining substantially uniformrotational effort to said rolls respectively and a resultantsubstantially constant tension on said web during said variations in therespective speeds of the rolls.

ALPHEUS O. HURXTHAL.

